A multi-country collaboration reports that inserting an asymmetric molecule (DTCA) into an ultrathin self-assembled monolayer within inverted perovskite solar cells breaks symmetry, enabling a co-assembly with a symmetric SAM (MeO-2PACz) that boosts efficiency and stability.

Using quantitative AFM-IR, researchers directly measured SAM surface coverage at the nanoscale to objectively evaluate coating performance.

Devices employing the MeO-DTCA SAM achieved certified efficiencies exceeding 25.6%, with peak cells reaching about 26.3% and 25.3%, and an encapsulated device retained 93% of its initial efficiency after roughly 1,150 hours at maximum power.

The Nature Communications study, spanning teams from China, Australia, the UK, South Korea, and Germany, highlights improved buried-interface quality and reduced non-radiative losses as key drivers of performance gains.

The co-assembly approach suppresses molecular self-aggregation and increases surface coverage, achieving 82.4% coverage for the MeO-DTCA combination versus 60.6% for MeO-2PACz alone, with a 4:1 MeO-2PACz:DTCA ratio yielding the best results.

Beyond single devices, researchers aim to apply the symmetry-breaking co-assembly concept to large-area modules and tandem solar cells, while expanding the library of symmetry-breaking molecular pairs and developing design rules linking symmetry, dipole moment, and surface coverage.